[asterisk-bugs] [Asterisk 0018021]: T.38 Fax Fallback to Pass-Through didn't work

[Asterisk Bug Tracker]

A NOTE has been added to this issue. 
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https://issues.asterisk.org/view.php?id=18021 
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Reported By:                sybasesql
Assigned To:                
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Project:                    Asterisk
Issue ID:                   18021
Category:                   Channels/chan_sip/T.38
Reproducibility:            always
Severity:                   minor
Priority:                   normal
Status:                     acknowledged
Asterisk Version:           1.6.2.13 
JIRA:                       SWP-2285 
Regression:                 No 
Reviewboard Link:            
SVN Branch (only for SVN checkouts, not tarball releases): N/A 
SVN Revision (number only!):  
Request Review:              
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Date Submitted:             2010-09-21 07:22 CDT
Last Modified:              2010-09-22 03:23 CDT
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Summary:                    T.38 Fax Fallback to Pass-Through didn't work
Description: 
Dear All!

OS: CentOS 5.5 x86_64
Asterisk: 1.6.2.13 x86_64

[ISP]--SIP--[ASTERISK]
ISP: T.38 fallback g711alaw
ASTERISK: t38pt_udptl=no

I have problem with T.38 reinvite: When we received reinvite from ISP, we
answered 488 Not accptable here and ASTERISK begin send UDPTL instead of
G711 RTP.

I attached call trace to view in wireshark.

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 (0127269) sybasesql (reporter) - 2010-09-22 03:23
 https://issues.asterisk.org/view.php?id=18021#c127269 
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Added an excerpt from the RFC3261 for this behavior:

14.1:
"If a UA receives a non-2xx final response to a re-INVITE, the session
parameters MUST remain unchanged, as if no re-INVITE had been issued."

But ASTERISK begin send UDPTL packets instead of RTP G711 as seen from
attached trace file t38-fallback-pass-through.zip. 

Issue History 
Date Modified    Username       Field                    Change               
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2010-09-22 03:23 sybasesql      Note Added: 0127269                          
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